fraser61 Posted January 30, 2012 Share Posted January 30, 2012 Can someone please confirm if the plug gap is .014"-.018" or .028"-.032" just the MoD user manual quotes both. As I'm about to ditch the old plugs just want to make sure I gap the new ones correctly. Thanks Quote Link to comment Share on other sites More sharing options...
fv1609 Posted January 30, 2012 Share Posted January 30, 2012 I think you will find that the wider gap is for an unscreened system, the narrower gap is for plugs in a screened system. The reason being that there is less HT available in a screened system as it introduces significant capacitance. This means that in effect some of the HT is lost as it has to charge up this capacitance, so less HT means you need a narrower gap. Quote Link to comment Share on other sites More sharing options...
ruxy Posted January 30, 2012 Share Posted January 30, 2012 (edited) Take care ! We have been here more than once, I am aware that the spark plug point gap in "User Instructions" going back to Rover marks 8.9. 10 & 11 + Rover 1 (S2A Lightweight) states 0.015" to 0.018". This instruction ran over into S3 3/4 ton 109" & S3 Lightweight User Manuals - then in the later ones it was amd. to 0.029" to 0.032" There have been a few plug offerings from the 19'60's into the 19'80's including P suffix (platinum types) eg RSN13P I have a museum of NOS FFR type plugs somewhere with copious notes. ISTR I was finding them set new very accurate at 0.031" Aahaa You would be unwise to re-gap a new plug. Somewhere - I have a good stock of new RSN13P (I stopped using them) , IIRC they also had 0.031" gaps , will have a good search around and double-check this dims. Can't find them in the airing cupboard , most others but not RSN13P - if they are in my office then they are lost for ever. =================================== ISTR - the reason is that there were specific plugs that did indeed have a new gap of 0.015" to 0.018" BUT these were for 7:1 CR engines in the S2A days Unfortunately - at the time of my research (yes, I listed all Rover & Champion + Lodge plug numbers with NSN Ref. alongside) I could not find this particular plug , described as :- Champion RSN BPA Replacement sparking plugs for the above given as :- LV6/MT4/3343 or LV6/MT4/79698 I suspect these were obsoleted donkeys years ago BUT you may find NOS, I don't recall ever having a RSN BPA in my hands ever ? Edited January 30, 2012 by ruxy speling Quote Link to comment Share on other sites More sharing options...
fv1609 Posted January 30, 2012 Share Posted January 30, 2012 BTW Don't try adjusting the gap on a RSN13P as there is a very real risk of snapping off the side contact or worse still weakening it & then it fails in the engine! What type are the new plugs you are going to fit? Quote Link to comment Share on other sites More sharing options...
ruxy Posted January 30, 2012 Share Posted January 30, 2012 Can't find the RSN13P plugs , however going through the notes I made in the past - they were gapped new at .40mm (0.0157") , so take your pick of 15 or 16 thou. The service life of platinum plugs is supposedly far longer than normal types, AFAIK the main advantage is that - electrons leap away from the tip of a small dia. with a sharp edge more willing than fatter & eroded round tips , thus less voltage is required to form a spark. ISTR - these claims were one of the reason I jacked using the RSN13P , as less voltage required means more voltage available. So this is like a sports coil - where you must open the gap wider than standard to get the full benefits , seems a bit of confliction ??? Quote Link to comment Share on other sites More sharing options...
fraser61 Posted January 31, 2012 Author Share Posted January 31, 2012 Thanks fellas for the initial responses, the plot thickens as nearly always it does. I will be replacing with Champion RSN12s. The engine is the 8:1CR type. Cheers Fraser Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 31, 2012 Share Posted January 31, 2012 I worked in REME workshops for a good many years, and in all that time, both working on Land Rovers and building engines for them, I never saw RSN13P plugs used in a FFR engine, always RSN12Y. So where has this all come from, as I do not think it was an official use, the RSN13P was specifically for RR B range and J60 engines. Quote Link to comment Share on other sites More sharing options...
fraser61 Posted January 31, 2012 Author Share Posted January 31, 2012 Richard What is your guidance as to the plug gap for the RSN12Y plug for the application previously described? Thanks Fraser Quote Link to comment Share on other sites More sharing options...
ruxy Posted January 31, 2012 Share Posted January 31, 2012 (edited) I worked in REME workshops for a good many years, and in all that time, both working on Land Rovers and building engines for them, I never saw RSN13P plugs used in a FFR engine, always RSN12Y. So where has this all come from, as I do not think it was an official use, the RSN13P was specifically for RR B range and J60 engines. ============== A very good question, I myself have removed them from direct release MOD FFR's , also I suspect dodgy info. from eBay sales & where vendors give a long list of supersession numbers where RSN13P has somehow been included to shift a load of dead stock LoL Edited January 31, 2012 by ruxy speling Quote Link to comment Share on other sites More sharing options...
ruxy Posted January 31, 2012 Share Posted January 31, 2012 I worked in REME workshops for a good many years, and in all that time, both working on Land Rovers and building engines for them, I never saw RSN13P plugs used in a FFR engine, always RSN12Y. So where has this all come from, as I do not think it was an official use, the RSN13P was specifically for RR B range and J60 engines. ============== A very good question, I myself have removed them from direct release MOD FFR's , also I suspect dodgy info. from eBay sales & where vendors give a long list of supersession numbers where it has somehow been included to shift a load of dead stock LoL Quote Link to comment Share on other sites More sharing options...
ruxy Posted January 31, 2012 Share Posted January 31, 2012 FWIW , the latest official Land Rover parts list I have to hand RTC9968FA dated June 1993 This list parts for both early & late DZS4A dizzy Plugs :- 566713 , this is listed specifically for 7:1 cr (I doubt if you have a low cr head fitted ? ) -------------------- or RTC 4732 , 8:1 cr I have just broken the seal on a Land Rover Genuine Parts box and removed the plug. it is gapped .80mm (.0315") The body is branded Lodge SRL14L "Made in England" ISRT Lodge went bonk quite a few years ago, IIRC of late I have seen the brand name Lodge used on a car type of plug I fitted to a Fiat , the plugs were marked as made in Italy , IIRC I checked up and they were Magneti Marelli manuf. I will continue to search for new plugs, I have some more recent stock , ISTR also RTC 4732 but I think these may in fact have Land Rover as the name brand ? Quote Link to comment Share on other sites More sharing options...
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